Filter assembly having an outer filter element and an inner filter element removably installed within the outer filter element

ABSTRACT

A filter assembly for filtering water in spas, swimming pools, hot tubs and whirlpools, having a first or outer filter element, a second or inner filter element removably installed within the outer filter element, a first coupling member associated with the outer filter element, a second coupling member associated with the inner filter element, the first and second coupling members engaging one another to connect the inner filter element with the outer filter element, and a releasable detent arrangement resisting disengagement of the first and second coupling members from one another. The outer filter element includes a filter medium for mechanically removing particulates from a fluid to be treated and the inner filter element includes a filter medium containing fluid purifying particles.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/411,600, filed Oct. 22, 2016, the entire disclosure of which isincorporated herein by reference.

FIELD

This invention relates to fluid filters and filter systems. Moreparticularly. This invention relates to filters and filter systems forfiltering water in spas, swimming pools, hot tubs and whirlpools.

BACKGROUND

Particulate filters, such as sand beds, are used in filter systems ofswimming pools, spas, hot tubs and whirlpools, to trap and removeparticulate contaminants from the water. Chlorine is used in thesefilter systems to kill harmful bacteria, algae and fungus that typicallyinfect the water.

The particulate filter must be periodically back-flushed to clear it ofaccumulated debris, often requiring that the filter system be taken downfor a period of time during the back-flushing. The chlorine used to killharmful bacteria, algae and fungus in the water causes a strong chlorineodor to permeate the area around the pool or spa. This odor becomesespecially objectionable when the spa or pool is located indoors,because the odor becomes concentrated and the area must be ventilated tokeep the chlorine odors down. The chlorine also attacks certain plasticsand fibers, causing deterioration and bleaching of pool or spaaccessories, as well as swimming or spa apparel. In addition, users ofthe pool or spa must shower or bathe to remove the chlorine after usingthe pool or spa.

Accordingly, a need exists for a filter that allows the use of chlorineto be substantially reduced or eliminated, to maintain safe, filteredwater, free of harmful bacteria in spas or pools and that does notrequire extensive maintenance, such as back-flushing.

SUMMARY

Disclosed herein is a filter assembly for filtering water in, forexample, spas and swimming pools. The filter assembly comprises a firstfilter element, a second filter element removably installed within thefirst filter element, a first coupling member associated with the firstfilter element, a second coupling member associated with the secondfilter element, the first and second coupling members engaging oneanother to connect the second filter element with the first filterelement, and a releasable detent arrangement resisting disengagement ofthe first and second coupling members from one another.

In some embodiments, the first and second coupling members rotatablyengage one another. In some embodiments, the engagement or thedisengagement of the first and second coupling members requires lessthan or more than 360 degrees of rotation and typically about 90 degreesof rotation.

In some embodiments, the first and second coupling members include oneof: a continuous thread or a thread segment on one of the first andsecond filter elements and a corresponding continuous thread or acorresponding thread segment on the other one of the first and secondfilter elements; a continuous thread or a thread segment on one of thefirst and second filter elements and a corresponding continuous grooveor a corresponding segment on the other one of the first and secondfilter elements; and a lug on one of the first and second filterelements and a corresponding groove or a corresponding groove segment onthe other one of the first and second filter elements.

In some embodiments, the releasable detent arrangement includes a firstdetent member associated with the first filter element and a seconddetent member associated with the second filter element.

In some embodiments, the first detent member includes one of anindentation and a bump provided on a pedestal disposed on an end cap ofthe first filter element, wherein the second detent member includes theother one of the indentation and the bump provided on an abutmentsurface of a handle of the second filter element, and wherein thereleasable detent arrangement resists the disengagement of the first andsecond coupling members from one another when the bump is disposed inthe indentation. In some embodiments, the releasable detent arrangementreleases when a rotational torque applied to one of the first and secondfilter elements is sufficient to cause the bump to move out of theindentation.

In some embodiments, the second filter element includes a filter mediumcomprising a fluid purifying particles. In some embodiments, the fluidpurifying particles are formed of an alloy of copper and zinc.

In some embodiments, the second filter element further includes a handlestructure and a filter medium depending from the handle structure. Insome embodiments, the handle structure includes a closure member and ahandle member extending from the closure member, the closure memberincluding the second coupling member. In some embodiments, the closuremember includes a skirt having an annular circumferential surface andwherein the second coupling member includes one of: a continuous threador a thread segment provided on the circumferential surface of theskirt; a continuous groove or a groove segment provided in thecircumferential surface of the skirt; and a lug provided on thecircumferential surface of the skirt.

In some embodiments, the first filter element further includes a filtermedium for mechanically removing particulates from a fluid to betreated. In some embodiments, the first filter element further includesan upper end cap and a lower end cap, the filter medium disposed betweenthe upper and lower end caps, the upper end cap including an opening forremovably inserting the second filter element within the first filterelement.

In some embodiments, the first filter element further includes an endcap having an opening for removably inserting the second filter elementwithin the first filter element, the opening having a surface whichincludes the first coupling member, the first coupling member includingone of a continuous thread or a thread segment, a continuous groove or agroove segment, and a lug.

In some embodiments, the first filter element further includes an endcap having an opening for removably inserting the second filter elementwithin the first filter element, the first coupling member disposedwithin the opening of the end cap.

In some embodiments, the first coupling member comprises a filter lockinsert having an annular circumferential surface, the filter lock insertincluding one of: a continuous thread or a thread segment provided onthe circumferential surface of the filter lock insert; a continuousgroove or groove segment provided in the circumferential surface of thefilter lock insert; and a lug provide on the circumferential surface ofthe filter lock insert.

In some embodiments, the first filter element includes an end cap havingan opening for removably attaching the first filter element to a filtersystem.

In some embodiments, the first filter element includes an end cap havingan opening and a connector disposed within the opening for removablyattaching the first filter element to a filter system.

Further disclosed herein is a filter element for a filter assemblycomprising a coupling member for engaging a corresponding couplingmember of a second filter element of the filter assembly, to connect thefilter element with the second filter element when the second filterelement is removably installed within the filter element. The couplingmember includes one of: a continuous thread or a thread segment; acontinuous groove or a groove segment; and a lug; and a detent memberfor resisting disengagement of the coupling member from thecorresponding coupling member of the second filter element when thesecond filter element is installed within the filter element.

Still further disclosed herein is a filter element for a filter assemblycomprising a coupling member for engaging a corresponding couplingmember of a second filter element of the filter assembly, to connect thefilter element with the second filter element when the filter element isremovably installed within the second filter element. The couplingmember includes one of: a continuous thread or a thread segment; acontinuous groove or a groove segment; and a lug; and a detent memberfor resisting disengagement of the coupling member from thecorresponding coupling member of the second filter element when thefilter element is installed within the second filter element.

BRIEF DESCRIPTION OF THE DRAWING

The disclosure is best understood from the following detaileddescription when read in conjunction with the accompanying drawing. Itis emphasized that, according to common practice, the various featuresof the drawing are not necessarily to scale. On the contrary, thedimensions of the various features may be arbitrarily expanded orreduced for clarity. Like numerals denote like features throughout thespecification and the drawing.

FIG. 1A is a top isometric view of a filter assembly according to anembodiment of the invention comprising a first or outer filter elementand a removable second or inner filter element shown being removed orinserted into the outer filter element.

FIG. 1B is a top isometric view of the filter assembly of FIG. 1A,wherein the inner filter element is shown installed within the outerfilter element and coupled therewith.

FIG. 1C is a bottom isometric view of the filter assembly.

FIG. 2A is a front or rear elevational view of the filter assembly.

FIG. 2B is a left or right elevational view of the filter assembly.

FIG. 2C is a top plan view of the filter assembly with the inner filterelement removed from the outer filter element.

FIG. 2D is a bottom plan view of the outer filter element.

FIG. 3A is an exploded cross-sectional view of the filter assembly.

FIG. 3B is an assembled cross-sectional view of the filter assembly.

FIG. 4A is a left or right elevational cross-sectional view of an upperend cap of the outer filter element of the filter assembly according toan embodiment of the invention.

FIG. 4B is a front or rear elevational view of the upper end cap of theouter filter element of the filter assembly.

FIG. 4C is a left or right elevational view of the upper end cap of theouter filter element of the filter assembly.

FIG. 5A is a front or rear elevational view of a lower end cap of theouter filter element of the filter assembly according to an embodimentof the invention.

FIG. 5B is a left or right elevational view of the lower end cap of theouter filter element of the filter assembly.

FIG. 5C is an elevational cross-sectional view of the lower end cap ofthe outer filter element of the filter assembly.

FIG. 5D is an elevational view of the lower end cap of the outer filterelement of the filter assembly according to another embodiment of theinvention.

FIG. 5E is an elevational cross-sectional view through line 5E-5E ofFIG. 5D.

FIG. 6A is a bottom isometric view of a filter washer associated withthe upper end cap of the outer filter element of the filter assemblyaccording to an embodiment of the invention.

FIG. 6B is an elevational view of the filter washer.

FIG. 6C is a bottom plan view of the filter washer.

FIG. 6D is a top plan view of the filter washer.

FIG. 6E is an elevational cross-sectional view through line 6E-6E ofFIG. 6B.

FIG. 7A is a top isometric view of a filter lock insert associated withthe upper end cap of the outer filter element of the filter assemblyaccording to an embodiment of the invention.

FIG. 7B is an elevational view of the filter lock insert.

FIG. 7C is a top plan view of the filter lock insert.

FIG. 7D is a bottom plan view of the filter lock insert.

FIG. 7E is an elevational cross-sectional view through line 7E-7E ofFIG. 7B.

FIG. 8A is a top isometric view of the inner filter element of thefilter assembly according to an embodiment of the invention.

FIG. 8B is a bottom isometric view of the inner filter element.

FIG. 8C is a front or rear elevational view of the inner filter element.

FIG. 8D is a left or right elevational view of the inner filter element.

FIG. 9A is a top isometric view of an embodiment of a handle structureof the inner filter element according to an embodiment of the invention.

FIG. 9B is a top plan view of the handle structure.

FIG. 9C is a bottom plan view of the handle structure.

FIG. 9D is a front or rear elevational view of the handle structure.

FIG. 9E is a left or right elevational view of the handle structure.

FIG. 10A is a top isometric view of a bottom end cap of the inner filterelement according to an embodiment of the invention.

FIG. 10B is a top plan view of the bottom end cap.

FIG. 10C is a bottom plan view of the bottom end cap.

FIG. 10D is an enlarged view of a central portion of the bottom end capshown in FIG. 10C.

FIG. 10E is an elevational cross-sectional view through line 10E-10E ofFIG. 10B.

FIGS. 11A and 11B are top plan views of the filter assembly depictingthe operation of coupling and detent arrangements of the filterassembly.

DETAILED DESCRIPTION

FIGS. 1A-1C collectively illustrate an embodiment of a filter assembly20 according to the invention. As illustrated in FIGS. 1A and 1B, thefilter assembly 20 includes a first or outer filter element 30 and aremovable second or inner filter element 40. The filter assembly 20 canhave a round cylindrical configuration, as shown in FIGS. 1A-1C, or anyother suitable configuration. The outer filter element 30 is constructedto operate as a micro filter for mechanically removing particulates froma fluid to be treated. The inner filter element 40 constructed tooperate as a fluid purifying filter for electrochemically changing thefluid chemistry and creating an environment that is deadly to somemicroorganisms and which interferes with the ability of manymicroorganisms to reproduce. The filter assembly 20 is intended, withoutlimitation, for filtering water in spas, swimming pools, hot tubs, andwhirlpools. For example, the filter assembly 20 can be used in a filtersystem for a spa and/or swimming pool, such as disclosed in U.S. Pat.No. 6,962,660 to Wybo, the disclosure of which is incorporated herein byreference. One of ordinary skill in the art will of course appreciatethat the filter assembly 20 can also be used for filtering water andother fluids in other applications.

Referring to FIG. 2A, the outer filter element 30 comprises a porousfilter medium or membrane 32, which is configured to define an interiorspace 38 (FIG. 3A) for receiving a core 44 containing a filter medium 46of the inner filter 40 (FIG. 3B). The porous filter membrane 32 can bemade of a fibrous material, such as polyester fibers (for example wovenor as a non-woven felt), and can be folded into a plurality of pleats 34extending lengthwise along the filter assembly 20. The pleats 34 provideincreased surface area for filtering and extend the life of the filter.The porous filter membrane 32 can have a porosity which is selected totrap particles as small as 20 microns in size.

As illustrated in, for example, in FIGS. 2A and 2B, the porous filtermembrane 32 is disposed between non-porous upper and lower end caps 21and 26, respectively. The end caps 21 and 26 can be formed from apolymer resin, such as polyurethane, and upper and lower ends 33 and 35,respectively, of the porous filter membrane 32 can be attached andsealed to the end caps 21 and 26, respectively, by embedding them intothe resin. This ensures a fluid tight joint between the porous filtermembrane 32 and the end caps 21 and 26 in order to define a flow paththrough the porous filter membrane 32, wherein all of the unfilteredfluid passes through the porous filter membrane 32, thereby preventingany bypass of unfiltered fluid at the junctions of ends 33 and 35 of theporous filter membrane 32 and the end caps 21 and 26, respectively.

Referring to FIGS. 3A and 3B, a perforated support tube or core 36 ispositioned immediately adjacent to or against the inner side of theporous filter membrane 32 and surrounds the interior space 38. The core36 can be attached at its ends to the end caps 21 and 26. The core 36radially supports the porous filter membrane 32 and maintains the endcaps 21 and 26 in spaced relation at either end of the outer filterelement 30.

As best illustrated in FIGS. 1A, 3A, and 3B, the upper end cap 21 of theouter filter element 30 has a central opening 23, which allows the core44 containing the filter medium 46 of the inner filter 40 to be insertedinto the interior space 38 defined by the porous filter membrane 32 ofthe outer filter element 30.

Referring now to FIGS. 4A-4C, the upper end cap 21 of the outer filterelement 30 includes a filter washer 60 seated in the central opening 23,a filter lock insert 70 seated on the filter washer 60, and an insertretaining collar 80 extending up from an top surface 22 of the end cap21 for retaining the filter washer 60 and the filter lock insert 70 tothe upper end cap 21.

As illustrated in FIGS. 1A, 4B and 4C, the top surface 22 of the outerfilter element end cap 21 includes two pedestals 100 which are disposedopposite to one another. One or both pedestals 100 include detentlocking member or elements 103 (e.g., indentations) of a detentarrangement, which are provided in or on upper surfaces 101 of thepedestals 100.

Referring to FIGS. 6A-6E, the filter washer 60 includes an annularportion 62 and a collar portion 68 depending from an innercircumferential edge 64 of the annular portion 62. The filter washer 60define an opening 66. When the filter washer 60 is seated in the centralopening 23 of the upper end cap 21, the collar portion 68 extendsthrough the central opening 23 and the annular portion 62 lies on thetop surface 22 of the end cap 21, illustrated in FIG. 4A.

Referring to FIGS. 7A-7D, the filter lock insert 70 has an annular body71 that includes an outer circumferential surface 72, an innercircumferential surface 73, a top surface 77, and a bottom surface 79.The filter lock insert 70 defines an opening 89. A circular flange 75extends about the outer circumferential surface 72 of the annular body71 at a lower end 74 thereof. The inner circumferential surface 73 ofthe body 71 is provided with one or more coupling members, which can bea male or female component of a bayonet coupling arrangement. Twocoupling members are depicted in the embodiment illustrated in FIGS. 7A,7C, and 7D, where each coupling member is the female component of thebayonet coupling arrangement comprising a groove 76 formed in the innercircumferential surface 73 of the annular body 71 between the top andbottom surfaces 77, 79 thereof, which extends about 90 degrees. Anopening 78 can be proved in the top surface 77 of the annular body 71 atthe trailing end of each groove 76 to allow insertion of thecorresponding male coupling member component of the bayonet couplingarrangement (e.g., lug 55 of the inner filter element 40 as illustratedin FIG. 9D). When two grooves 76 are used, they may be disposed oppositeone another, as shown in FIGS. 7A and 7C.

In other embodiments, the one or more coupling members provided on or inthe inner circumferential surface 73 of the annular body 71 of thefilter lock insert 70 can each include the male coupling membercomponent of the bayonet coupling arrangement instead of the femalecomponent. In such embodiments, each male coupling member component cancomprise a lug similar to the lug 55 illustrated in FIG. 9D. In stillother embodiments, each coupling member provided on or in the innercircumferential surface 73 of the annular body 71 of the lock insert 70can comprise a thread segment or a continuous thread or groove extendingless than, equal to, or more than 360 degrees (not shown).

Referring again to FIG. 4A, the insert retaining collar 80 surrounds thecentral opening 23 of the upper end cap 21. The insert retaining collar80 includes an annular wall 82 extending up from the top surface 22 ofthe upper end cap 21 and a circular retaining flange 86 at an upper end84 of the annular wall 82. A recessed ring-shape seating surface 24 isprovided in the portion of the top surface 22 of the upper end cap 21located between the central opening 23 and the annular wall 82. Theseating surface 24 receives the annular portion 62 of the filter washer60. The circular retaining flange 86 of the insert retaining collar 80and the annular portion 62 of the filter washer 60 define a spacetherebetween (not visible) for receiving the flange 75 of the lockinsert 70.

Referring again to FIGS. 2C, 3A, and 4A, the opening 23 of the upper endcap 21, the opening 89 of the lock insert 70, and the opening 66 of thefilter washer 60 are coaxially aligned to define an aperture 90, whichpermits the inner filter element 40 to be inserted through the upper cap21 and installed within the interior space 38 of the outer filterelement's porous filter membrane 32. When installed within the interiorspace 38, the filter medium 46 of the inner filter element 40 can filterand treat fluid that has passed through and been first filtered by theporous filter membrane 32.

Referring now to FIGS. 1C. 2D, and 5A-5E, the lower end cap 26 of theouter filter element 30 has a central opening 27 that allows fluidcommunication with the interior space 38 (FIG. 3A) defined by the outerfilter element's porous filter membrane 32, and a connector 28non-removably disposed within the central opening 27 for removablymounting the filter assembly 20 to a filter system (not shown) of a spa,a swimming pool, or the like. The connector 28 can comprising externallythreaded collar as shown, or an internally threaded collar (not shown).In other embodiments, the lower end cap 26 can comprise an internallythreaded collar 280 (FIGS. 9A and 9B) or an externally threaded collar(not shown) that is unitarily formed with the lower end cap 26 andsurrounds the opening 27 in the end cap 26 of the outer filter element30, and is operative as a connector.

Referring now to FIGS. 8A-8C, the inner filter element 40 comprises ahandle structure 42, a perforated support tube or core 44 extending fromthe lower end of the handle structure 42, a bottom end cap 48 thatcloses and seals the open lower end of the core 44, and a porous filtermedium 46 disposed within the core 44, and extending between the lowerend of the handle structure 42 and the bottom end cap 48.

Referring to FIG. 9A-9E, the handle structure 42 includes a closuremember 50 and a handle member 54, which can be unitarily formed with theclosure member 50. The closure member 50 includes a circular top wall 51and an annular skirt 53 depending from the bottom of the top wall 51.The outer circumferential surface 57 of the annular skirt 53 has one ormore coupling members 55 which is/are configured to engage the couplingmember(s) 76 of the outer filter element 30 (FIG. 7A), to connect theinner filter element 40 with the outer filter element 30. Each couplingmember can be the corresponding male or female component of the earliermentioned bayonet coupling arrangement associated with the outer filterelement 30. Two male coupling members of the earlier mentioned bayonetcoupling arrangement are depicted in the embodiment illustrated in FIGS.9C-9E, where each coupling member comprises a lug 55 provided on theouter circumferential surface 57 of the annular skirt 53 of the handlestructure closure member 50. The lugs 55 threadedly engage the groovesegments 76 formed in the inner circumferential surface 73 of theannular body 71 of the outer filter element lock insert 70. When twolugs 55 are used, they may be disposed on opposite sides of the annularskirt 53, as illustrated in FIGS. 9C and 9D.

In other embodiments, the one or more coupling members provided on or inthe outer circumferential surface 57 of the annular skirt 53 of thehandle structure closure member 50 can each include the female couplingmember component of the bayonet coupling arrangement instead of the malecomponent (when the outer filter element 30 includes the malecomponent). In such embodiments, each female coupling member componentcan comprise a groove similar to the groove 76 shown in FIG. 7A. Instill other embodiments, each coupling member provided on or in theouter circumferential surface 57 of the annular skirt 53 of the handlestructure closure member 50 can comprise a thread segment or acontinuous thread or groove extending less than, equal to, or more than360 degrees (not shown).

Referring again to FIG. 9D, the circular top wall 51 of the handlestructure closure member 50 may have an outer diameter which is slightlylarger than the outer diameter of the annular skirt 52. This allows anoverhanging portion 52 of the circular top wall 51 to cover and engagethe top surface 77 of the filter lock insert 70 when the inner filterelement 40 is coupled to the outer filter element 30, as illustrated inFIG. 2A. This arrangement prevents unfiltered fluid from entering theinterior space 38 of the outer filter element porous filter membrane 32through the aperture 90 defined by upper end cap opening 23, the filterlock insert 70 and filter washer 60, which unfiltered fluid could clogthe porous filter medium 46 of the inner filter 40.

Referring still to FIGS. 9D and 9E, the handle member 54 extends overthe closure member 50 and defines opposing first and second abutment endsurfaces 56 which merge with the bottom surface of the overhangingportion 52 of the circular top wall 51. The first and second abutmentend surfaces 56 overlie and can engage corresponding ones of thepedestals 100 provided on the top surface 22 of the upper end cap 21when the inner filter 40 is assembled with the outer filter 30, asillustrated in FIGS. 11A and 11B. Detent locking members or elements 102(illustrated as bumps in FIGS. 9D and 9E) of the earlier mentioneddetent arrangement, are provided on or in one or both of the abutmentend surfaces 56 of the handle member 54. The detent arrangement resistsrelative rotation between the coupled outer and inner filter elements30, 40 when the detent locking element(s) 103 provided in or on theupper surface(s) 101 of the pedestals 100 of the outer filter elementupper end cap 21 (FIG. 2C) engage the detent locking element(s) 102provided on or in the abutment end surfaces 56 of the inner filterelement handle member 54 (FIG. 9D), unless a sufficient amount ofrotational torque is applied to the handle member 54 of the inner filter40, which causes the bump(s) 102 to move out of the indentation(s) 103,thereby preventing the inner filter element 40 from inadvertentlyuncoupling from the outer filter element 30 when the filter assembly 20is in use. Accordingly, the coupling arrangement and locking detentarrangement operate together to releasably couple the outer filterelement 30 with the inner filter element 40.

Referring to FIGS. 10A-10E, the bottom end cap 48 includes a top wall110 and a side wall 112 extending from the circumferential edge of thetop wall 110. A centrally located tube 114 extends up from an interiorsurface 111 of the top wall 110. The tube 114 defines a channel 115 thatfluidly communicates with an outlet opening 116 in the top wall 110. Thechannel 115 of the tube 114 and the outlet opening 116 in the top wall110 allow any air contained inside the filter medium 46 and/or any fluidthat passes through the filter medium 46, to exit the inner filter 40into the interior space 38 of the outer filter element porous filtermembrane 32.

Referring again to FIGS. 8A-8D, the core 44 of the inner filter elementhandle structure 42 has an upper end 45 that is non-removably orremovably inserted into or otherwise connected with the annular skirt 53of the closure member 50 and a lower end 47 is that non-removably orremovably inserted into or otherwise connected the bottom end cap 48.The filter medium 46 is disposed in and supported by the core 44. Theopenings in the core 44 of the inner filter element 40 allow fluid(which has passed through and been filtered by the porous filtermembrane 32 of the outer filter 30) flowing through the interior space38 to contact and flow into and out of the filter medium 46. Thefiltered fluid then exits the outer filter element 30 through theopening 27 in the connection element 28, and into the filter system (notillustrated).

The filter medium 46 of the inner filter element 40 can be folded,wrapped or rolled into a rod or cylindrical shaped element containedwithin the core 44. The porous filter medium 46 can be made of a fibrousmaterial, such as layers of woven polyester fibers or non-wovenpolyester felt laminated together. A particulate fluid purifying mediumcan be randomly distributed and captured within the filter medium 46.The purifying medium can comprise irregularly shaped particles (notshown) formed of an alloy of copper and zinc as described in U.S. Pat.Nos. 5,135,654; 5,198,118 and 5,314,623, all to Heskett, the disclosuresof which are incorporated herein by reference.

In operation, the fluid purifying medium creates an electrochemicalreaction in the spa water known as an oxidation-reduction reaction asthe water contacts and/or passes through the filter medium 46. The metalalloy comprising the medium exchanges valence electrons with otherelements and compounds in the water thereby changing the water chemistryand creating an environment which is deadly to some microorganisms andwhich interferes with the ability of many microorganisms to reproduce.Thus the oxidation-reduction reactions effected by the medium killalgae, fungi, and bacteria. The reactions also remove undesiredcompounds such as calcium carbonate and hydrogen sulfide from the water.The medium helps stabilize the pH of the water and removes heavy metalssuch as copper, lead and mercury, which tend to plate onto the surfaceof the medium. Free chlorine is converted into a water-soluble chloride,thereby providing safe, odor-free water in a spa or pool.

Referring again to FIGS. 3A, 3B, 4A, and 91), the inner filter element40 can be installed in the outer filter element 30 by inserting the core44 of the inner filter element 40 containing the porous filter medium 46through the aperture 90 defined by the lock insert 70 and filter washer60 of the outer filter element upper end cap 21. Next, the couplingmembers of the inner filter element 40 are engaged with the couplingmembers of the outer filter element 30. In embodiments where thecoupling members of the inner filter element 40 are the earlierdescribed lugs 55 and the coupling members of the outer filter element30 are the earlier described groove segments 76, coupling is achieved byaligning and inserting the lugs 55 of the inner filter element handlestructure 42 into the groove segments 76 through the openings 78 in thetop surface 77 of the outer filter element lock insert at the trailingend of each groove 76. Then, as illustrated in FIGS. 11A and 11B, theinner filter element 40 is rotated (e.g., clockwise) relative to theouter filter element 30 using the handle member 54 thereby causing thelugs 55 to travel toward the leading end of the grooves 76. As the lugs55 approach the leading end of the grooves 76 near the end of therotation, the first and second abutment end surfaces 56 of the handlemember 54 slide over the upper surfaces 101 of the pedestals 100 of theupper end cap 21 such that the detent locking elements 102 and 103lockingly engage one another. This process is reversed when uncouplingand removing the inner filter element 40 from the outer filter element30. In some embodiments the amount of rotation required to couple/engageor uncouple/disengage the coupling members to install or remove theinner filter 40, is about 90 degrees.

The coupling and detent arrangements of the outer and inner filterelements of the filter assembly and the connector of the lower end cap,as described above, allow the inner filter element to be removed fromand installed in the outer filter element without having to disconnectthe outer filter element from the filter system of the spa, swimmingpool, hot tub or whirlpool. This feature makes it very easy andconvenient to replace the inner filter element, which typically requiresreplacement more often than the outer filter element of the filterassembly.

It should be understood that the invention is not limited to theembodiments illustrated and described herein. Rather, the appendedclaims should be construed broadly to include other variants andembodiments of the invention, which may be made by those skilled in theart without departing from the scope and range of equivalents of theinvention. It is indeed intended that the scope of the invention shouldbe determined by proper interpretation and construction of the appendedclaims and their legal equivalents, as understood by those of skill inthe art relying upon the disclosure in this specification and theattached drawings.

What is claimed is:
 1. A filter assembly comprising: a first filterelement including an end cap having an opening; a second filter elementremovably installed within the first filter element through the openingin the end cap of the first filter element; a first coupling memberdisposed within the opening of the end cap of the first filter element;a second coupling member associated with the second filter element, thefirst and second coupling members engaging one another to connect thesecond filter element with the first filter element; and a releasabledetent arrangement resisting disengagement of the first and secondcoupling members from one another, the releasable detent arrangementincluding one of an indentation and a bump on the first filter elementand the other one of the indentation and the bump on the second filterelement.
 2. The filter assembly of claim 1, wherein the first and secondcoupling members rotatably engage one another.
 3. The filter assembly ofclaim 2, wherein the engagement or the disengagement of the first andsecond coupling members requires less than or more than 360 degrees ofrotation.
 4. The filter assembly of claim 2, wherein the engagement orthe disengagement of the first and second coupling members requiresabout 90 degrees of rotation.
 5. The filter assembly of claim 2, whereinthe first and second coupling members include one of: a continuousthread or a thread segment on one of the opening of the end cap of thefirst filter element and the second filter elements and a correspondingcontinuous thread or a corresponding thread segment on the other one ofthe opening of the end cap of the first filter element and the secondfilter elements; a continuous thread or a thread segment on one of theopening of the end cap of the first filter element and the second filterelements and a corresponding continuous groove or a correspondingsegment on the other one of the opening of the end cap of the firstfilter element and the second filter elements; and a lug on one of theopening of the end cap of the first filter element and the second filterelements and a corresponding groove or a corresponding groove segment onthe other one of the opening of the end cap of the first element and thesecond filter elements.
 6. The filter assembly of claim 1, wherein thesecond filter element includes a filter medium comprising fluidpurifying particles.
 7. The filter assembly of claim 6, wherein thefluid purifying particles are formed of an alloy of copper and zinc. 8.The filter assembly of claim 1, wherein the second filter elementfurther includes a handle structure and a filter medium depending fromthe handle structure.
 9. The filter assembly of claim 8, wherein thehandle structure includes a closure member and a handle member extendingfrom the closure member, the closure member including the secondcoupling member.
 10. The filter assembly of claim 9, wherein the closuremember includes a skirt having an annular circumferential surface andwherein the second coupling member includes one of: a continuous threador a thread segment provided on the circumferential surface of theskirt; a continuous groove or a groove segment provided in thecircumferential surface of the skirt; and a lug provided on thecircumferential surface of the skirt.
 11. The filter assembly of claim1, wherein the first filter element further includes a filter medium formechanically removing particulates from a fluid to be treated.
 12. Thefilter assembly of claim 11, wherein the end cap of the first filterelement is an upper end cap and wherein the first filter element furtherincludes a lower end cap, the filter medium disposed between the upperand lower end caps, the upper end cap including the opening forremovably inserting the second filter element within the first filterelement.
 13. The filter assembly of claim 12, wherein the first filterelement further includes another end cap having an opening for removablyattaching the first filter element to a filter system.
 14. The filterassembly of claim 12, wherein the first filter element further includesanother end cap having an opening and a connector disposed within theopening for removably attaching the first filter element to a filtersystem.
 15. The filter assembly of claim 1, wherein the opening of theend cap defines a surface which includes the first coupling member, thefirst coupling member including one of: a continuous thread or a threadsegment; a continuous groove or a groove segment; and a lug.
 16. Thefilter assembly of claim 1, wherein the first coupling member comprisesa filter lock insert having an annular circumferential surface, thefilter lock insert including one of: a continuous thread or a threadsegment provided on the circumferential surface of the filter lockinsert; a continuous groove or s groove segment provided in thecircumferential surface of the filter lock insert; and a lug provide onthe circumferential surface of the filter lock insert.
 17. The filterassembly of claim 1, wherein the first filter element includes an endcap, the end cap having a pedestal disposed thereon, the pedestalincluding the one of the indentation and the bump of the releasabledetent arrangement, wherein the second filter element includes a handle,the handle having an abutment surface, the abutment surface includingthe other one of the indentation and the bump of the releasable detentarrangement, and wherein the releasable detent arrangement resists thedisengagement of the first and second coupling members from one anotherwhen the bump is disposed in the indentation.
 18. The filter assembly ofclaim 17, wherein the releasable detent arrangement releases when arotational torque applied to one of the first and second filter elementsis sufficient to cause the bump to move out of the indentation.
 19. Afilter assembly comprising: a first filter element including an end caphaving an opening; a second filter element for removable insertionwithin the first filter element through the opening in the end cap ofthe first filter element; a first coupling member disposed within theopening of the end cap of the first filter element; a second couplingmember associated with the second filter element, the first and secondcoupling members engaging one another when the second filter element isremovably installed within the first filter element; and a releasabledetent arrangement for resisting disengagement of the first and secondcoupling members from one another when the second filter element isinstalled within the first filter element, the releasable detentarrangement including one of an indentation and a bump on the firstfilter element and the other one of the indentation and the bump on thesecond filter element.
 20. A filter assembly comprising: a first filterelement including an end cap and first and second pedestals disposed onthe end cap; a second filter element removably installed within thefirst filter element, the second filter element including a handlehaving a first abutment surface at a first end thereof and a secondabutment surface at a second end thereof; a first coupling memberassociated with the first filter element; a second coupling memberassociated with the second filter element, the first and second couplingmembers engaging one another to connect the second filter element withthe first filter element; and a releasable detent arrangement resistingdisengagement of the first and second coupling members from one another;wherein the releasable detent arrangement includes a first detentmembers associated with the first filter element and a second detentmembers associated with the second filter element; and wherein the firstdetent members each includes one of an indentation and a bump providedon a corresponding one of the pedestals disposed on the end cap of thefirst filter element, wherein the second detent member includes theother one of the indentation and the bump provided on a correspondingone of the abutment surfaces of the handle of the second filter element,and wherein the releasable detent arrangement resists the disengagementof the first and second coupling members from one another when the bumpis disposed in the indentation.